Vitamin C (Ascorbic acid)

Vitamin C, also known as ascorbic acid, was discovered in 1912 and, in 1933, was the first vitamin to be synthesized in the laboratory. It is required for hundreds of processes within the body. A powerful antioxidant, it helps protect body cells and tissues against damage from free radicals. It is vital for maintaining a healthy immune system – it is used up more quickly by the body during infections, an indication of its importance in immune function.

Vitamin C is a co-factor in several enzymatic reactions and is involved in the formation of collagen, a pre-requisite for healthy bones, cartilage, teeth, skin and the blood vessels and capillaries. It helps promote tissue repair and wound healing. It is a natural laxative.

Vitamin C’s antioxidant effects may also offer some protection against some forms of cancer and heart disease. It may help reduce cholesterol levels and normalise blood pressure and is involved in the production of haemoglobin in red blood cells and in the absorption of iron from food. Long-term supplementation may help prevent the formation of cataracts. There is some evidence that regular supplementation may also ease the symptoms and shorten the duration of the common cold. However, the mega-dosing theory is now, to a large degree, discredited – clinical studies have shown that very large doses of Vitamin C taken at the first signs of a cold have no effect on the severity and duration of symptoms.

Vitamin C must be obtained from the diet every day. A water-soluble vitamin, it cannot be stored by the body. The European Food Safety Authority recommends 110mg per day for men and 95mg for women, and a balanced and varied diet rich in fruit and vegetables should provide adequate amounts. The best sources are citrus fruits, berries, tomatoes, peppers, green leafy vegetables and potatoes (skin-on). Boiling, overcooking, light and prolonged storage can all deplete the Vitamin C content of food. Fruit and vegetables frozen immediately after harvesting are likely to have a much higher Vitamin C content than their ‘fresh’ shop-bought counterparts languishing for days under bright lights.

Rosehips are a particularly rich source of Vitamin C. During World War II, and on into the 1960s, schools and organisations such as the Scouts, Guides and Women’s Institutions were encouraged by the Ministry of Health to collect rosehips for conversion into rosehip syrup.

Vitamin C deficiency ultimately leads to scurvy, the symptoms of which include lethargy, fatigue, painful joints, bleeding gums, easy bruising, slow healing wounds and lowered immunity. The scientific name of this vitamin – ascorbic acid – is derived from the word anti-scorbutic, or anti-scurvy. Scurvy was a common cause of death amongst crewmen on long sea voyages. The anti-scorbutic effects of citrus fruits were known as early as the fifteenth century and, in 1747, the Royal Naval surgeon James Lind undertook an early clinical trial in which some crewmen received normal rations and others were issued with two oranges and a lemon daily. The results conclusively proved that citrus fruit could prevent scurvy (although Vitamin C itself would not be identified for another 250 years). By the end of the eighteenth century lemon juice was being issued to all Royal Navy crewmen. Lime juice was used during Caribbean voyages, hence the nickname ‘Limeys’ given to British sailors.

Nowadays, those most at risk of scurvy include people with mental disorders, unusual eating habits, alcoholics, diabetics and elderly people living alone. Smoking also depletes body levels of Vitamin C, largely because smoke inhalation causes oxidative damage that uses up increased quantities of the vitamin.

The most commonly used compounds in Vitamin C supplements are ascorbic acid, sodium ascorbate and calcium ascorbate. Taking more than 1000mg of a Vitamin C supplement daily may cause nausea and diarrhoea, stomach cramps and flatulence. Symptoms will quickly ease on reducing or ceasing supplementation. High doses can also interfere with the absorption of selenium and copper. People suffering from kidney diseases may have to limit their daily intake.